A method of synthesizing 5-aminotetrazole (hereinafter referred to as "5-AT") is described by R. Stolleet al., "Zur Kenntnis des Amino-5-terazols," Chem. Ber., vol 62, pp.1118-26, (1929). According to the procedure of Stolle, 5 -AT is obtained by reacting aqueous hydrazoic acid (HN.sub.3) and dicyandiamide (NH.sub.2 C(NH)NHCN). A significant disadvantage of Stolle's procedure is the need for initial large quantities of hydrazoic acid. Hydrazoic acid is highly explosive and is also a potent vasodilator which can adversely affect the health of workers exposed to it.
More recently, Joseph S. Mihina and Robert M. Herbst, "The Reaction of Nitriles with Hydrazoic Acid: Synthesis of Monosubstituted Tetrazoles," Journal of Organic Chemistry, pp. 1082-92, (1950), discloses a variation of Stolle's procedure. According to Mihina et al., a suspension of dicyandiamide and sodium azide was heated to 65.degree. C. Concentrated hydrochloric acid was added in small portions with frequent manual agitation. After complete addition of the acid, the mixture was kept at 65.degree.-70.degree. C. for 6 hours during which the product began to crystallize. The semi-solid mass was allowed to stand overnight and was chilled thoroughly before being filtered and washed with ice water. Although the Mihina et al. procedure avoids producing initially large quantities of hydrazoic acid by adding the hydrochloric acid in small portions over time, hydrazoic acid is still, nevertheless, produced and the procedure is cumbersome and protracted.
It will be appreciated that it would be a significant advancement in the art to provide rapid, simple processes for synthesizing 5-AT which do not require or produce large quantities of hydrazoic acid.
Such processes for preparing 5-AT are disclosed and claimed herein.